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IYPT Elements

IYPT 2019 Elements 091: Protactinium: Scarcity and geological dating

Element 91 in our International Year of the Periodic Table series is protactinium. Protactinium is a scarce and radioactive element which finds use in the dating of sediments.

At this point, we’re approaching the part of the periodic table where element scarcity limits their uses. Protactinium is one of these rare elements with few applications, which came very close to being named the most boring element in a recent paper in Nature.

Luckily for protactinium, there are still some interesting things about it. Its name isn’t one of those – it means ‘precursor of actinium’, which is due to one of its radioactive decay products being actinium. Slightly more interesting is the use of one of its isotopes, protactinium-231, in the radiometric dating of sediments up to 175,000 years old.

More interesting still is the fact that, despite its scarcity, you probably have some protactinium in your home. Home smoke alarms use small amounts of radioactive americium (we’ll come to that in a few elements’ time), and protactinium is one of americium’s decay products. So, while you’ll never be able to see it, protactinium isn’t as far away as you might think – pretty interesting after all.

Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.